/* pngwtran.c - transforms the data in a row for PNG writers
 *
 * Last changed in libpng 1.4.1 [February 25, 2010]
 * Copyright (c) 1998-2010 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
 * and license in png.h
 */

#include "png.h"
#define PNG_NO_PEDANTIC_WARNINGS
#ifdef PNG_WRITE_SUPPORTED
    #include "pngpriv.h"

/* Transform the data according to the user's wishes.  The order of
 * transformations is significant.
 */
void /* PRIVATE */
png_do_write_transformations(png_structp png_ptr)
{
    png_debug(1, "in png_do_write_transformations");

    if (png_ptr == NULL)
        return;

    #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
    if (png_ptr->transformations & PNG_USER_TRANSFORM)
        if (png_ptr->write_user_transform_fn != NULL)
            (*(png_ptr->write_user_transform_fn)) /* User write transform
                                                     function */
                (png_ptr,              /* png_ptr */
                &(png_ptr->row_info),  /* row_info:     */
                /*  png_uint_32 width;          width of row */
                /*  png_uint_32 rowbytes;       number of bytes in row */
                /*  png_byte color_type;        color type of pixels */
                /*  png_byte bit_depth;         bit depth of samples */
                /*  png_byte channels;          number of channels (1-4) */
                /*  png_byte pixel_depth;       bits per pixel (depth*channels) */
                png_ptr->row_buf + 1); /* start of pixel data for row */
    #endif
    #ifdef PNG_WRITE_FILLER_SUPPORTED
    if (png_ptr->transformations & PNG_FILLER)
        png_do_strip_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
                            png_ptr->flags);
    #endif
    #ifdef PNG_WRITE_PACKSWAP_SUPPORTED
    if (png_ptr->transformations & PNG_PACKSWAP)
        png_do_packswap(&(png_ptr->row_info), png_ptr->row_buf + 1);
    #endif
    #ifdef PNG_WRITE_PACK_SUPPORTED
    if (png_ptr->transformations & PNG_PACK)
        png_do_pack(&(png_ptr->row_info), png_ptr->row_buf + 1,
                    (png_uint_32)png_ptr->bit_depth);
    #endif
    #ifdef PNG_WRITE_SWAP_SUPPORTED
    if (png_ptr->transformations & PNG_SWAP_BYTES)
        png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1);
    #endif
    #ifdef PNG_WRITE_SHIFT_SUPPORTED
    if (png_ptr->transformations & PNG_SHIFT)
        png_do_shift(&(png_ptr->row_info), png_ptr->row_buf + 1,
                     &(png_ptr->shift));
    #endif
    #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
    if (png_ptr->transformations & PNG_SWAP_ALPHA)
        png_do_write_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
    #endif
    #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
    if (png_ptr->transformations & PNG_INVERT_ALPHA)
        png_do_write_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
    #endif
    #ifdef PNG_WRITE_BGR_SUPPORTED
    if (png_ptr->transformations & PNG_BGR)
        png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1);
    #endif
    #ifdef PNG_WRITE_INVERT_SUPPORTED
    if (png_ptr->transformations & PNG_INVERT_MONO)
        png_do_invert(&(png_ptr->row_info), png_ptr->row_buf + 1);
    #endif
}

    #ifdef PNG_WRITE_PACK_SUPPORTED
/* Pack pixels into bytes.  Pass the true bit depth in bit_depth.  The
 * row_info bit depth should be 8 (one pixel per byte).  The channels
 * should be 1 (this only happens on grayscale and paletted images).
 */
void /* PRIVATE */
png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
{
    png_debug(1, "in png_do_pack");

    if (row_info->bit_depth == 8 &&
        row_info->channels == 1)
    {
        switch ((int)bit_depth)
        {
            case 1:
            {
                png_bytep sp, dp;
                int mask, v;
                png_uint_32 i;
                png_uint_32 row_width = row_info->width;

                sp = row;
                dp = row;
                mask = 0x80;
                v = 0;

                for (i = 0; i < row_width; i++)
                {
                    if (*sp != 0)
                        v |= mask;
                    sp++;
                    if (mask > 1)
                        mask >>= 1;
                    else
                    {
                        mask = 0x80;
                        *dp = (png_byte)v;
                        dp++;
                        v = 0;
                    }
                }
                if (mask != 0x80)
                    *dp = (png_byte)v;
                break;
            }
            case 2:
            {
                png_bytep sp, dp;
                int shift, v;
                png_uint_32 i;
                png_uint_32 row_width = row_info->width;

                sp = row;
                dp = row;
                shift = 6;
                v = 0;
                for (i = 0; i < row_width; i++)
                {
                    png_byte value;

                    value = (png_byte)(*sp & 0x03);
                    v |= (value << shift);
                    if (shift == 0)
                    {
                        shift = 6;
                        *dp = (png_byte)v;
                        dp++;
                        v = 0;
                    }
                    else
                        shift -= 2;
                    sp++;
                }
                if (shift != 6)
                    *dp = (png_byte)v;
                break;
            }
            case 4:
            {
                png_bytep sp, dp;
                int shift, v;
                png_uint_32 i;
                png_uint_32 row_width = row_info->width;

                sp = row;
                dp = row;
                shift = 4;
                v = 0;
                for (i = 0; i < row_width; i++)
                {
                    png_byte value;

                    value = (png_byte)(*sp & 0x0f);
                    v |= (value << shift);

                    if (shift == 0)
                    {
                        shift = 4;
                        *dp = (png_byte)v;
                        dp++;
                        v = 0;
                    }
                    else
                        shift -= 4;

                    sp++;
                }
                if (shift != 4)
                    *dp = (png_byte)v;
                break;
            }
        }
        row_info->bit_depth = (png_byte)bit_depth;
        row_info->pixel_depth = (png_byte)(bit_depth * row_info->channels);
        row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
                                          row_info->width);
    }
}
    #endif

    #ifdef PNG_WRITE_SHIFT_SUPPORTED
/* Shift pixel values to take advantage of whole range.  Pass the
 * true number of bits in bit_depth.  The row should be packed
 * according to row_info->bit_depth.  Thus, if you had a row of
 * bit depth 4, but the pixels only had values from 0 to 7, you
 * would pass 3 as bit_depth, and this routine would translate the
 * data to 0 to 15.
 */
void /* PRIVATE */
png_do_shift(png_row_infop row_info, png_bytep row, png_color_8p bit_depth)
{
    png_debug(1, "in png_do_shift");

    if (
        row_info->color_type != PNG_COLOR_TYPE_PALETTE)
    {
        int shift_start[4], shift_dec[4];
        int channels = 0;

        if (row_info->color_type & PNG_COLOR_MASK_COLOR)
        {
            shift_start[channels] = row_info->bit_depth - bit_depth->red;
            shift_dec[channels] = bit_depth->red;
            channels++;
            shift_start[channels] = row_info->bit_depth - bit_depth->green;
            shift_dec[channels] = bit_depth->green;
            channels++;
            shift_start[channels] = row_info->bit_depth - bit_depth->blue;
            shift_dec[channels] = bit_depth->blue;
            channels++;
        }
        else
        {
            shift_start[channels] = row_info->bit_depth - bit_depth->gray;
            shift_dec[channels] = bit_depth->gray;
            channels++;
        }
        if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
        {
            shift_start[channels] = row_info->bit_depth - bit_depth->alpha;
            shift_dec[channels] = bit_depth->alpha;
            channels++;
        }

        /* With low row depths, could only be grayscale, so one channel */
        if (row_info->bit_depth < 8)
        {
            png_bytep bp = row;
            png_uint_32 i;
            png_byte mask;
            png_uint_32 row_bytes = row_info->rowbytes;

            if (bit_depth->gray == 1 && row_info->bit_depth == 2)
                mask = 0x55;
            else if (row_info->bit_depth == 4 && bit_depth->gray == 3)
                mask = 0x11;
            else
                mask = 0xff;

            for (i = 0; i < row_bytes; i++, bp++)
            {
                png_uint_16 v;
                int j;

                v = *bp;
                *bp = 0;
                for (j = shift_start[0]; j > -shift_dec[0]; j -= shift_dec[0])
                {
                    if (j > 0)
                        *bp |= (png_byte)((v << j) & 0xff);
                    else
                        *bp |= (png_byte)((v >> (-j)) & mask);
                }
            }
        }
        else if (row_info->bit_depth == 8)
        {
            png_bytep bp = row;
            png_uint_32 i;
            png_uint_32 istop = channels * row_info->width;

            for (i = 0; i < istop; i++, bp++)
            {

                png_uint_16 v;
                int j;
                int c = (int)(i % channels);

                v = *bp;
                *bp = 0;
                for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
                {
                    if (j > 0)
                        *bp |= (png_byte)((v << j) & 0xff);
                    else
                        *bp |= (png_byte)((v >> (-j)) & 0xff);
                }
            }
        }
        else
        {
            png_bytep bp;
            png_uint_32 i;
            png_uint_32 istop = channels * row_info->width;

            for (bp = row, i = 0; i < istop; i++)
            {
                int c = (int)(i % channels);
                png_uint_16 value, v;
                int j;

                v = (png_uint_16)(((png_uint_16)(*bp) << 8) + *(bp + 1));
                value = 0;
                for (j = shift_start[c]; j > -shift_dec[c]; j -= shift_dec[c])
                {
                    if (j > 0)
                        value |= (png_uint_16)((v << j) & (png_uint_16)0xffff);
                    else
                        value |= (png_uint_16)((v >> (-j)) & (png_uint_16)0xffff);
                }
                *bp++ = (png_byte)(value >> 8);
                *bp++ = (png_byte)(value & 0xff);
            }
        }
    }
}
    #endif

    #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
void /* PRIVATE */
png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
{
    png_debug(1, "in png_do_write_swap_alpha");

    {
        if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
        {
            /* This converts from ARGB to RGBA */
            if (row_info->bit_depth == 8)
            {
                png_bytep sp, dp;
                png_uint_32 i;
                png_uint_32 row_width = row_info->width;
                for (i = 0, sp = dp = row; i < row_width; i++)
                {
                    png_byte save = *(sp++);
                    *(dp++) = *(sp++);
                    *(dp++) = *(sp++);
                    *(dp++) = *(sp++);
                    *(dp++) = save;
                }
            }
            /* This converts from AARRGGBB to RRGGBBAA */
            else
            {
                png_bytep sp, dp;
                png_uint_32 i;
                png_uint_32 row_width = row_info->width;

                for (i = 0, sp = dp = row; i < row_width; i++)
                {
                    png_byte save[2];
                    save[0] = *(sp++);
                    save[1] = *(sp++);
                    *(dp++) = *(sp++);
                    *(dp++) = *(sp++);
                    *(dp++) = *(sp++);
                    *(dp++) = *(sp++);
                    *(dp++) = *(sp++);
                    *(dp++) = *(sp++);
                    *(dp++) = save[0];
                    *(dp++) = save[1];
                }
            }
        }
        else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
        {
            /* This converts from AG to GA */
            if (row_info->bit_depth == 8)
            {
                png_bytep sp, dp;
                png_uint_32 i;
                png_uint_32 row_width = row_info->width;

                for (i = 0, sp = dp = row; i < row_width; i++)
                {
                    png_byte save = *(sp++);
                    *(dp++) = *(sp++);
                    *(dp++) = save;
                }
            }
            /* This converts from AAGG to GGAA */
            else
            {
                png_bytep sp, dp;
                png_uint_32 i;
                png_uint_32 row_width = row_info->width;

                for (i = 0, sp = dp = row; i < row_width; i++)
                {
                    png_byte save[2];
                    save[0] = *(sp++);
                    save[1] = *(sp++);
                    *(dp++) = *(sp++);
                    *(dp++) = *(sp++);
                    *(dp++) = save[0];
                    *(dp++) = save[1];
                }
            }
        }
    }
}
    #endif

    #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
void /* PRIVATE */
png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
{
    png_debug(1, "in png_do_write_invert_alpha");

    {
        if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
        {
            /* This inverts the alpha channel in RGBA */
            if (row_info->bit_depth == 8)
            {
                png_bytep sp, dp;
                png_uint_32 i;
                png_uint_32 row_width = row_info->width;
                for (i = 0, sp = dp = row; i < row_width; i++)
                {
                    /* Does nothing
                     *(dp++) = *(sp++);
                     *(dp++) = *(sp++);
                     *(dp++) = *(sp++);
                     */
                    sp += 3; dp = sp;
                    *(dp++) = (png_byte)(255 - *(sp++));
                }
            }
            /* This inverts the alpha channel in RRGGBBAA */
            else
            {
                png_bytep sp, dp;
                png_uint_32 i;
                png_uint_32 row_width = row_info->width;

                for (i = 0, sp = dp = row; i < row_width; i++)
                {
                    /* Does nothing
                     *(dp++) = *(sp++);
                     *(dp++) = *(sp++);
                     *(dp++) = *(sp++);
                     *(dp++) = *(sp++);
                     *(dp++) = *(sp++);
                     *(dp++) = *(sp++);
                     */
                    sp += 6; dp = sp;
                    *(dp++) = (png_byte)(255 - *(sp++));
                    *(dp++) = (png_byte)(255 - *(sp++));
                }
            }
        }
        else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
        {
            /* This inverts the alpha channel in GA */
            if (row_info->bit_depth == 8)
            {
                png_bytep sp, dp;
                png_uint_32 i;
                png_uint_32 row_width = row_info->width;

                for (i = 0, sp = dp = row; i < row_width; i++)
                {
                    *(dp++) = *(sp++);
                    *(dp++) = (png_byte)(255 - *(sp++));
                }
            }
            /* This inverts the alpha channel in GGAA */
            else
            {
                png_bytep sp, dp;
                png_uint_32 i;
                png_uint_32 row_width = row_info->width;

                for (i = 0, sp = dp = row; i < row_width; i++)
                {
                    /* Does nothing
                     *(dp++) = *(sp++);
                     *(dp++) = *(sp++);
                     */
                    sp += 2; dp = sp;
                    *(dp++) = (png_byte)(255 - *(sp++));
                    *(dp++) = (png_byte)(255 - *(sp++));
                }
            }
        }
    }
}
    #endif

    #ifdef PNG_MNG_FEATURES_SUPPORTED
/* Undoes intrapixel differencing  */
void /* PRIVATE */
png_do_write_intrapixel(png_row_infop row_info, png_bytep row)
{
    png_debug(1, "in png_do_write_intrapixel");

    if (
        (row_info->color_type & PNG_COLOR_MASK_COLOR))
    {
        int bytes_per_pixel;
        png_uint_32 row_width = row_info->width;
        if (row_info->bit_depth == 8)
        {
            png_bytep rp;
            png_uint_32 i;

            if (row_info->color_type == PNG_COLOR_TYPE_RGB)
                bytes_per_pixel = 3;
            else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
                bytes_per_pixel = 4;
            else
                return;

            for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
            {
                *(rp) = (png_byte)((*rp - *(rp + 1)) & 0xff);
                *(rp + 2) = (png_byte)((*(rp + 2) - *(rp + 1)) & 0xff);
            }
        }
        else if (row_info->bit_depth == 16)
        {
            png_bytep rp;
            png_uint_32 i;

            if (row_info->color_type == PNG_COLOR_TYPE_RGB)
                bytes_per_pixel = 6;
            else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
                bytes_per_pixel = 8;
            else
                return;

            for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
            {
                png_uint_32 s0 = (*(rp) << 8) | *(rp + 1);
                png_uint_32 s1 = (*(rp + 2) << 8) | *(rp + 3);
                png_uint_32 s2 = (*(rp + 4) << 8) | *(rp + 5);
                png_uint_32 red = (png_uint_32)((s0 - s1) & 0xffffL);
                png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
                *(rp) = (png_byte)((red >> 8) & 0xff);
                *(rp + 1) = (png_byte)(red & 0xff);
                *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
                *(rp + 5) = (png_byte)(blue & 0xff);
            }
        }
    }
}
    #endif /* PNG_MNG_FEATURES_SUPPORTED */
#endif /* PNG_WRITE_SUPPORTED */